MANCHESTER — Conservative activist James E. O'Keefe III trumpeted his brand of guerilla-style citizen journalism Thursday night while promoting his best-selling book that includes a chapter on his attempts to show New Hampshire has weak voter identification laws.

"You have to support independent, citizen ... groups to do the work," the New Jersey resident told some 40 people at a book-signing and fundraiser for the New Hampshire House Republican Victory PAC at the Radisson Hotel.

"There is an enormous demand for investigative reporting in this country because the media won't do it," he added.

O'Keefe's nonprofit advocacy group, "Project Veritas," attempted to show the state had weak voter identification laws during the 2012 elections by giving supporters the names of dead Granite Staters, then sending them into polling places where they received ballots.

A web video of the incidents went public, inciting controversy. The move helped prompt the then-Republican-led Legislature to strengthen the state's voter ID law last year.

As a result, O'Keefe said he became the target of the state Department of Justice's attempt to prosecute him. He said Associate Attorney General Richard Head "raided a colleague's house" while armed with "criminal grand jury subpoenas."

"He was working with the FBI to try to prosecute me. As many as seven federal agents working with the Department of Justice tried to shut me down," he said at the $50 per person fundraiser.

"They are trying to cannibalize journalism," O'Keefe said.

Head this week said his office closed its investigation of O'Keefe for potential voter fraud without charging him.

O'Keefe devoted a chapter in his book — "Breakthrough: Our Guerrilla War to Expose Fraud and Save Democracy" — to Head. Head, he added, refused to sign the chapter in his book, a New York Times best seller.

"Our goal is to make society more ethical and transparent. But you have to break through a media firewall to do it," he said, claiming "the media" is fearful of taking on government and other organizations.

State Rep. William O'Brien, R-Mont Vernon, who is considering a run for Congress, introduced O'Keefe as a "muckraker" and "champion of free speech."